/Engine/Source/Runtime/ApplicationCore/Public/GenericPlatform/GenericApplication.h
virtual bool TryCalculatePopupWindowPosition ( const [FPlatformRect](API\Runtime\ApplicationCore\GenericPlatform\FPlatformRect) & InAnchor, const FVector2D & InSize, const FVector2D & ProposedPlacement, const [EPopUpOrientation::Type](API\Runtime\ApplicationCore\GenericPlatform\EPopUpOrientation__Type) Orientation, FVector2D *const CalculatedPopUpPosition ) const